Zimbra Collaboration Suite up to 10.1.20 Email HTML Sanitizer cross-site request forgery

Summaryinfo

A vulnerability has been found in Zimbra Collaboration Suite up to 10.1.20 and classified as problematic. Impacted is an unknown function of the component Email HTML Sanitizer. Performing a manipulation results in cross-site request forgery. This vulnerability is known as CVE-2026-93630. Remote exploitation of the attack is possible. No exploit is available. The affected component should be upgraded.

Detailsinfo

A vulnerability classified as problematic has been found in Zimbra Collaboration Suite up to 10.1.20. This affects an unknown part of the component Email HTML Sanitizer. The manipulation with an unknown input leads to a cross-site request forgery vulnerability. CWE is classifying the issue as CWE-352. The web application does not, or can not, sufficiently verify whether a well-formed, valid, consistent request was intentionally provided by the user who submitted the request. This is going to have an impact on integrity. The summary by CVE is:

A hostname canonicalization vulnerability in the email HTML sanitizers of Zimbra Collaboration Suite (ZCS) allows an unauthenticated sender to bypass the restriction on forms that target the Zimbra host. DefangFilter and the OWASP ActionAttributePolicy compare the form-action hostname with the request hostname before browser URL canonicalization. A percent-encoded hostname can therefore survive sanitization while the browser submits the form to the normal Zimbra origin with the recipient's authentication cookie. This permits authenticated form requests from a crafted email after the recipient opens it in Classic and submits the form. The issue is present in ZCS 10.1.16 and 10.1.21. It does not bypass an endpoint's CSRF-token checks; a state-changing attack additionally requires an endpoint that accepts the resulting request without that protection.

The advisory is shared at wiki.zimbra.com. This vulnerability is uniquely identified as CVE-2026-93630 since 09/18/2026. The exploitability is told to be easy. It is possible to initiate the attack remotely. No form of authentication is needed for exploitation. It demands that the victim is doing some kind of user interaction. Neither technical details nor an exploit are publicly available.

Upgrading to version 10.1.21 eliminates this vulnerability.

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Productinfo

Type

• Groupware Software

Vendor

• Zimbra

Name

• Collaboration Suite

Version

• 10.1.0
• 10.1.1
• 10.1.2
• 10.1.3
• 10.1.4
• 10.1.5
• 10.1.6
• 10.1.7
• 10.1.8
• 10.1.9
• 10.1.10
• 10.1.11
• 10.1.12
• 10.1.13
• 10.1.14
• 10.1.15
• 10.1.16
• 10.1.17
• 10.1.18
• 10.1.19
• 10.1.20

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CPE 2.2info

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